Cement-burning process and apparatus therefor.



PATENTED FEB. 27, 1906.

.B. E. BLDRE'D. CEMENT BURNING PROCESS ANDAPPARATUS THEREFOR.

APPLICATION FILED SEPT. 9, 1904.

UNITED- STATES PATENT OFFICE.

BYRON E. ELDRED, OF BROOKLINE, MASSACHUSET' ASSIGNOR TO COMBUSTIONUTILITIES COMPANY, OF vNEYV YORK, N. Y., A COR- PORATION or NEW YORK.-

CEMENT-BURNING Pnocsss AND APPARATUS THEREFOR.

Patented Feb. 27, 1906.

ApplicationfiledSepteinber9.1904- Serial No. 223,879.

To all whom it may concern.-

Be it known that I, BYRON E. ELDRED, a

citizen of the United States, and aresident of Brookline, in the countyof Norfolk and State of Massachusetts, have invented certain new anduseful Improvements in Cement-Burning Processes and ApparatusThereforfof which the following is a specification.

7 naces with a long flame of high temperature,

' coal an usually roduced with a blast of powdered compressed air. Thisgave a very intense heat which erformed the calcination or'eliminationcarbonic-acid gas from the lime in the cement-forming material and alsofused or sintered the material into ce--- ment clinkers which thenpassed out of thekiln. Such a flame as ordinarily produced is difficultof regulation, destructive of the lining of the kiln, and wasteful offuel. I have discoveredthat much of the trouble in these respects is dueto employing the same flame or a pluralit of such flames for performingboth the ca cining and the clinkering,-. and that these difficulties canbe overcome by more or less separating the calcining and sinterin stepsand performing them by flames of di erent temperatures or by using aflame of low enough temperature to economically perform the calciningstep and modifying a portion of said flame to afford a sinteringtemperature.

Another feature of my invention consists in the discovery of a flame orheating agent applicable to cement-burning and possessing the necessarproperty or capability of affording are at1ve y low calcining heatsubi'ect to being raised to a sintering heat by coal intensification. Aflame of this character can be produced by the method described in myPatent No. 692,257 bypassing through .the-fuel-body a draft-current ofair and a small portion of the stack-gases or products of combustion(mainly nitrogen and carbon dioxid) from the kiln or furnace wherebytheflame is rendered voluminous,inflated, and

slow-burning, and-it may be locally intensi- Here-.

. fied in a desired region means of a highpressure gaseous jet, such asan air-jet, preferably directed upon the cement material near its exitfrom the kiln to afford the high temperature necessary to the productionof a bar clinker. The present application claims specifically theproduction of such a flame from an external fuel-bed and alsorertainapparatus useful or necessary to the performance of cement-burning withthis agent.

The invention is generically claimed in Referrin to the drawings, 10indicates a I rotary inclined cylinder whose interior constitutes thelaboratory or hearth-chamber of a reverberatory furnace forburningcement, the material being fed in at the end more remote from thefire-box 11 by a conveyor-12 and after traversing the cylinder-being(lischarged through anopening 13 into a cooler 14 in the usual way. L

15 is the grate of the firebox, on which the bed of fuel, preferablycoal, is supported, and 16 is the ash-pit below the grate, the doors 1718. of both fu'elechamber 19 and ash-pit 16 being preferably closedduring the operation of the furnace. From the stack 20 .a pipe 21 leadsback to the ash-pit 16 below the grate 15, and in this ipe is interposeda fan-blower 22, by whicfi a small portion of the products of combustionand calcinati'on are drawn back and forced through the fuel-bed on thegrate in company with a larger supply of air drawn into the pipe 2through an air-inlet 23, su bstantially as described in my aforesaidpatent, No. 692,257. The suction. pipe from the stack and the air-inlet23 are both provided with valves 24 25, whereby the volumes of air andneutral diluent in the draft-current may be maintained in predeterminedproportion.

From the fuel-.chamber19 two openings 27 r 28 leadinto the interior ofthe cylinder hearth-chamber 10, through both of which the flame andgases from the fuel-bed pass into said hearth-chamber, and between theseside of thecylinder up which the material is carried by the rotation ofsaid cylinder. An air-compressor 32', connected with this pipe,furnishes compressed air therethrough,

and a means of heating the air is provided by carrying the pi e as achamber 33 through the clinker-coo er 14. Any other suitable means forheating the air may be adopted as, for example, heating it on the reenerative.

Erinci le through regenerators t ei'nselves eate by the stack-gases inany suitable manner. Theheating of the air increases the activity of thelocalized combustion caused or promoted thereby.

In the operation of the invention the effect of the diluent derivedthrou h pipe 21 and passing through the ignited el-bed on the grate isto retard the combustion, the latter being sufficiently intense toproduce a large evolution of combustible gases from the fuel, but ofless intensity than the combustion of a fuel-bed or other body of fuelaccomplished with a similar draft of pure air. The thickness of thefuel-bed need be no greater than the ordinary, and in general enoughoxygen passes through the bed to eventually complete the combustion ofthe evolved gases, but owing to the dilution and inflation of theheating agent the combustible gases burn at an increased distance fromthe grate or seat of initial combustion, producing a long flame ofincreased volume, which fills the cross-section of the hearth-chamber toa greater degree than an ordinary flame, and hence comes nearer to thematerials on the floor of said chamber.

In this way the combustion of-the fuel is made much more eflicient andeconomical in respect to the materials under treatment than ,a flamewhich hugs the roof of the hearth chambcr. The maintenance of ignitionis insured by reason of the combustion taking place in an envelopingregion capable of attaining an igniting tem erature and furnished by thefire-brick wal s of-the hearth-chamber and by the materialsundertreatment, which latter in the case of'cement add to the heat by theirchemical action.

The flame produced with the diluent is one of a low heat intensity,particularly suited to the calcination of the lime in the cementformingmaterial, from which the carbon dioxid is by this process lar ely drivenoff before the final sintering or c inkerin takes place, For the latteraction a high heat is required, which I furnish through the agency ofthe jetdelivered by the nozzle 30. This jet acting on the heating agentissuing through the opening 28 stirs or agitates its ingredients,bringing them together in intimate relation and producing an intenselocalized area of combustion which has the effect of sintering thematerial approaching the discharge end of the cylinder 10, sai materialhaving been previously calcined by the cooler part of the flamein theouter end of the hearth-chamber. The function of the baffle 29 is toprotect the nozzle or jet-outlet 30 and prevent the flame and gasesissuing through the outlet 27 from being drawn into the region of thejet.

One of the advantages of using the diluent and dividing the calciningfrom the clinkering step is that the temperature of the flame and therate' of fuelconsumption may be more accurately regulated with respectto raft-mir- 1. The herein-described process which consists in passingover a body of cement forming material in an unobstructed reverbera- IOCtive chamber a flame su ported from an external fuel-bed and regu atedby means of a gaseous diluent passed through the'fuel, to a temperaturesuited to calcination but not to complete sintering of the material.

2. The herein-described process which consists in treating cementforming material with a low-temperature calcining-flame 'supported froman external fuel-bed, and sintering the material with a localhigh-temperature flame.

3. Process of burning cement which conslsts 1n sub ect1ng the materlalto a calcmmg- I flame produced from an eXternalfuel-bed' with a portionof stack-gases in the supplycurrent of the fire, and locallyintensifying a portion of said flame with agaseous jet to produce aclinkering temperature.

4; Process of burning cement which consists in feeding a stream of thecement-forming material along the hearth of a reverberative chamber,passing thereover' in an opposite direction a long slow-burning flamegiven off from an external fuel-bed through which is passed under forceddraft air and a portion of diluent stack-gases, and locally intensifyinga portion of said flame near the exit of the material by means ofa-transverse jet. ofair interce ting tse flame or gas-current and directe upon the material.

- '5. A cement-burning apparatus comprising a reverberativehearth-chamber having material on the hearth, and means for pro-' ducinga local high-temperature fia'me'to sinter the material near the end ofits travel.

6. A cement-furnace comprising a rotary inclined barrel, an externalfire-box opening into said barrel and having a fuel-support, means tosupply a diluent gas to said fire-box anterior to the fuel-support, ajet-nozzle com: manding the outlet of said fire-box and directed ontothe floor of said barrel, and a source of compressed air connected withsaid jet-nozzle.

7. A cement-kiln comprising a rotar in clined barrel having a stack atone en an external fire-box at the other end removable from the barreland having a conduit connection between its ash-pit and the stack, andan air-jet nozzle carried b the fire-box and commanding the outlet terefrom into the barrel.

8. A cement-kiln comprising a materialtreating flame-chamber, anexternal fire-box having a plurality of openings into said chamher, andan air-jet nozzle commanding one of said openings and arranged at anangle, to deflect the flame onto the floor of the chamber.

9. A cement-kiln comprising areverberative chamber, an external fire-boxhaving means for producing a slow-burning artificially-inflated flame, apartition dividing the outlet from said fire-box into a plurality ofportions, and a jet-nozzle mounted on said partition and commanding oneof the portions.

10. A furnace for burning cement and other materials comprising a rotaryinclined barrel having means for introducing the meterials at the upperend and removing them at the lower end, an external fire-box adapted toburn solid fuel and connected with one end of said barrel, meansforreturning a small portion of products of combustion to thedraft-chamber of the fire-box for retarding the combustion, and meansfor regulating the quantity of said products returned.

11. A furnace for burning cement and other materials comprising aworking chamher having means for advancing the material therethrough,means connected with said chamber for burning solid fuel externallythereof, means for formin separate flames at different points along saidchamber from the combustion of said fuel, and means for rendering one ofsaid flames substantially hotter than the other.

Signed at New York cit in the county of New York and State or" N ewYork, this 6th day of September, A. D. 1904.

BYRON E. ELDRED.

Witnesses:

CHAs. B. CRANE, L. T. SHAW.

